The present invention generally relates to integrated circuits, and, more particularly, to a finite impulse response filter.
Finite impulse response (FIR) filters are commonly used in digital signal processing applications such as image processing, audio processing, and video processing applications. FIR filters include decimation filters, interpolation filters, symmetric filters, and asymmetric filters. Decimation and interpolation filters change a sampling rate of input samples and hence, are multi-rate filters. Symmetric and asymmetric filters perform filtering without changing the sampling rate of the input samples and hence, are single-rate filters.
A decimation filter removes M−1 samples out of every M samples of an input signal, thereby down-sampling the input signal by a factor of M. An interpolation filter inserts L−1 samples between adjacent samples of an input signal, thereby up-sampling the input signal by a factor of L. In order to reduce the hardware required for interpolation and decimation, polyphase filters are used for achieving interpolation and decimation. A conventional interpolation filter cannot be used as decimation filter and a conventional decimation filter cannot be used as an interpolation filter. This leads to an increase in circuit area and power dissipation.
Techniques for overcoming the aforementioned problem involve configuring a programmable logic device (PLD) as an FIR filter. The PLD can be operated in either interpolation or decimation mode as required. However, this technique does not support run-time configurability for changing the number of filter taps. The technique also does not support use of polyphase filters, so still there is additional circuit area and power consumption. The technique also does not support cascading of two or more FIR filters and hence, cannot achieve quadrature error compensation.
It would be advantageous to have a FIR filter that supports run-time configurability, yet does not consume unnecessary power and area, and supports quadrature error compensation.